Gas blast circuit breaker with trap for products of arcing



Oct. 9, 1951 GAS BLAST CIRCUIT BREAKER WITH P. L. TAYLOR 2,570,610

TRAP FOR PRODUCTS 0F ARCING Filed Aug. 25, 1947 Patented Oct. 9, 1951 UNITED STATES PATENT OFFICE GAS BLAST CIRCUIT BREAKER WITH TRAP FOR PRODUCTS OF ARCING Application August 23, 1947, Serial No. 770,296

Claims.

This invention relates in general to improve-' ments in circuit breakers of the as blast type and more particularly to means for reducing the contamination of the gas blast, particularly the conv tamination produced by material removed from the contacts by the action of the arc.

In a circuit breaker, arc initiation occurring upon parting of the contacts is an explosion-like V phenomenon. Jets of melted and vaporized metal ward the contact gap and the zone wherein the arc is extended and extinguished.

About the time of current zero, the back pressure decreases, thus reducing the resistance which the arc extinguishing blast must overcome to decontaminate the arcing zone. During the time that that blast has been impeded by the back pressure of products of arcing, the gas under pressure may be contaminated by products of arcing, which diffuse or are projected in all directions, including upstream and downstream directions. It may thus happen that the contact gap and the arc extinguishing zone are being supplied with a blast of partly contaminated or ionized gas rather than a blast of clean gas having a high dielectric strength.

It is therefore an object of the present invention to provide a circuit breaker of the-gas blast type in which a large portion of the products of arcing is promptly removed from the gas blast.

Another object of the present invention is to provide a circuit breaker of the gas blast type in which products of arcing are directed toward a zone in which such products are trapped out of the main gas flow.

Another object of the present invention is to provide a circuit breaker of the gas blast type in which products of arcing are condensed and trapped by eddies produced in the gas flow by suitable configuration of the gas conduit.

Another object of the present invention is to provide a circuit breaker of the gas blast type in which products of arcing are temporarily stored outside of the blast serving to extinguish the arc. Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a view partly in elevation and partly in vertical cross section through one embodiment of the invention in which material removed from the contacts is directed into a zone of increased cross section of the blast forming a pocket;

Fig. 2 is a partial view in vertical cross section of a modified embodiment of the invention in which products of the are are directed toward a surface guiding the are products toward a pocket forming an eddy zone in the gas stream; and

Fig. 3 is a partial view in vertical cross section of a modified embodiment of the invention in which the products of arcing are directed into a pocket substantially abstracted from the gas stream.

Referring more particularly to the drawing by characters of reference, numerals 6, 1 designate a pair of insulators adapted to support the contacts 8, 9 of a circuit breaker of the gas blast type. Contact 8 is a fixed contact havingthe arcing portion thereof disposed within a hollow insulating member I I defining an elongated passage or contact chamber I2. Suitable are extinguishing gas such as air under suitable pressure obtained from a reservoir, not shown, may be caused to flow through chamber I2 to extinguish the are drawn between contacts 8, 9 upon separation thereof. Chamber I2 is built with a cross section of suitable size and configuration to cause the gas blast to reach the desired velocity, which preferably approaches the velocity of sound, as is well known.

Contact 9 is pivotally supported on insulator '1 and may be moved in and out of abutting engagement with contact 8 by means of a suitable motor, not shown, through a mechanism including a connecting rod I3. Leakage of gas about contact 9 through the wall of member I I may be reduced by the provision of labyrinth passages I 4.

The outlet of chamber I2 communicates with an arcing chamber I5 preferably defined by a tubular member I6 at least partly of insulating material. An insulatin barrier H, which may be of gas evolving material, is disposed within chamber I 5 to cause the path of the blast to present two enlarged zones l8, I9 separated by a constricted zone 20. The cooperating surfaces of contacts 8, 9 are in general alignment with zone I8.

When current is to be interrupted, contact 9 is moved out of engagement with contact 8. An are is drawn between the cooperating surfaces of the contacts. The are causes material of the contacts to be vaporized or otherwise removed with explosive force between the contacts. A large portion of the removed contact material, in the form of incandescent particles, metallic vapors, and clouds of metallic oxides, is guided ,products into zone [8.

3 by the cooperating surfaces of contacts 8, 9 and is sprayed as indicated by dotted lin 10 toward the surface of barrier l1 defining the enlarged zone I 8.

The contact material reaching zone 18 is subjected-to the deionizing action of the surface of barrier I! and is partly deposited on the wall of barrier l7 definin zone l8. Some of the contact material remains in suspension in the gas contained in zone l8. As a result of the pocketlike configuration of zone I8, the air flow forms therein an eddy which retains a large portion of the contact material out of the air stream, at least during the time required for finally interrupting the current. Another part of the contact'material is carried by the air stream into zone I9, wherein such material is trapped by another eddy formed by the gas stream.

The gas stream is thus stripped to a large extent'of contaminating material. After the first passage of the arc current through the value zero, the condition of the gas stream will be unfavorable for the re-establishment of a continuous bridge of ionized gas between contacts 8, 9. Reestablishment of the are between .the contacts will therefore be hindered to aconsiderable extent by the action of barrier 11.

In the embodiment partly illustrated in Fig. 2, the cooperating surfaces of contacts .8, .9 are in alignment witha surface 2| of barrier I I situated immediately adjacent the contacts on the downstream side thereof. The products of arcing,

ejected along a path indicated by dotted line '30,

collect along surface 2|, which surface directs the The latter again forms a pocket within which the collected and partly deionized are products are trapped to a large extent as in the embodiment illustrated .in Fig. 1. Some of the remaining are products are trapped in the eddy formed in zone I 9.

As shown in Fig. 2, the extinguishing action of the gas blast maybe assisted by the provision within chamber I5 of a probe 22 connected with one of contacts 8, 9 through a suitable resistor 23.

In theembodiment illustrated in Fig. 3, an insulating barrier 24, which maybe of ,gas evolving material, is disposed entirely within the gas stream. Barrier 24 defines a pocket 25, and the cooperating surfaces of contacts 8, 9 are in alignment with the opening of pocket 25. products are thus sprayed into the pocket, in which the gas blast forms-an eddy which retains a large portion of the are products during the arc interrupting process. Some of the arc products "are also carried by the gas blast through a constricted zone 26 defined by the walls of barrier 24 and member 16 and into an enlarged zone 21, in which the gas stream forms a second eddy in which such products of arcing are temporarily retained. The gas stream is thus stripped of a large portion of the contaminating material as :Philip L. Taylor, issued .August 26, 1947.

I claim: 1. .In a gas blast circuit breaker,.:passage-,defin- .ing wall means, a pair of relatively movable contacts arranged in the passage definedrby said wall The are means and adapted to form an arc gap therebetween upon separation thereof, means for establishing a blast of gas through said passage and gap, said passage-defining wall means including means defining a pocket situated downstream of said gap for receiving products of arcing, said pocket-defining means being arranged at the zone of intersection between the jet of products of arcing issuing from said gap and said passage-defining wall means.

2. In a gas blast circuit breaker, means defining a passage, a pair of abutting relatively movable contacts arranged to engage along a predetermined plane and adapted to form an arc gap therebetween upon separation thereof, means for establishing a blast of gas through said passage and gap, and pocket defining means in said passage arranged to intersect said plane formed by said contacts for receiving the products of arcing directly from said gap.

3. In a gas blast circuit breaker, means'defining a passage, a pair of abutting relatively movable contacts arranged in said passage and adapted .to form an arc gap therebetween upon separation thereof, said contacts engaging each other along a predetermined plane extending at an acute angle to the axis of said passage, means for establishing a blast of gas through said passage and gap, and pocket defining means arranged in said passage to intersect said plane for receiving the products of arcing directly from said gap.

4. In a gas blast circuit breaker, means defining a passage, a pair of cooperating relatively movable contacts arranged in said passage and adapted to form an arc gap therebetween upon separation thereof, means for establishing a blast of gas through said passage and gap, and pocket defining means arranged adjacent said gap for receiving and retaining the products of arcing issuing in a straight line from said gap.

5. In a gas blast circuit breaker, means defining a passage, a pair of relatively movable contacts arranged in said passage and adapted to form an arc gap therebetween upon separation thereof, means for establishing a blast of gas through said passage and gap, an insulating surface in close vicinity of said gap arranged generally in the direction of the jet of products of arcing issuing from said gap for guiding said products of arcing in a predetermined direction away from said gap, and insulating pocket means defining an eddy current zone for trapping and retaining in said pocket the products of arcing collected by said surface.

PHILIP L. TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,967,989 Clerc July 21, 1934 2,233,180 Petermichl Feb. 25, 1941 2,284,658 Hobson June 2, 1942 2,284,857 Bennett June 2, 1942 2,292,158 Prince Aug. 4, 1942 2,345,375 Bennett Mar. 28, 1944 2,349,681 Slepian May 23, 1944 2,426,250 Taylor Aug.26, 1-947 FOREIGN PATENTS Number Country Date 436,422 Great Britain Oct. 10, 1935 539,236 Great Britain Sept. 2, 1941 591,604 Germany Jan. 25, 1984 

